1. Field of Invention
The present invention relates to a motorcycle transmission and suspension system, and more particularly to a rear-wheels transmission and suspension system for motorcycle.
2. Description of Related Arts
Currently, there are three types of motorcycles: the most popular two-wheeled vehicle, also called motor bicycle; the three-wheeled vehicle, which is also known as motor tricycle; and the four-wheeled vehicle, which is frequently referred as all terrain vehicle (ATV).
Motor bicycle is a single track vehicle with a front wheel and a rear wheel generally. It is light weighted, flexible, and gas saving. That's why motor bicycle is very popular in both urban district and rural area. But the problem is two-wheeled vehicle is not stable, driving and parking it needs extra effort to keep balance. This makes people, especially senior person difficult to use.
Four-wheeled motorcycle, especially ATV is good in stability. It is suitable to be used in a wider variety of terrain. But the problem is the system of ATV is complex and heavy, and it also has to sacrifice the speed.
Three-wheeled motorcycle combines the merits of both two-wheeled and four-wheeled motorcycle. It is more stable, easy to ride, and is not expensive. Typically, a tricycle comprises a pair of rear wheels mounted on the opposite ends of a rear axle. While one of the problems for the tricycle is when the tricycle is making a turn at a curve, or driving on an uneven ground, the two rear wheels will bear unbalanced force. This requests the material of the suspension system to afford the force and not to deform which will increase the cost and weight of the suspension system.
The conventional suspension system of a tricycle comprises a swing arm carrying a bearing gear of the rear wheel axle. The rear wheel axle extends through the bearing gear transversely and has two rear wheels fixed at the two opposite ends thereof. Therefore the whole weight of the rear part of the vehicle is executed on the center point of the axle. Also, when the force executed on the two rear wheels are not even, the axle will afford twisting force. To bear these forces and not to be deformed, the axle needs to be strong and the length should be limited. While, the shorter the axle is, the less the stability is. The cost of the axle structure and the transmission and suspension system is relatively high.